[Guffey6]

Hey guys, I have a 1988 f250 7.3 and my gear shifter broke off right above the transmission (zf5) so I welded it back. I removed both battery negative cables before I started. The next couple of mornings I went to start the truck and had low voltage. Like 5.3 volts on the cranking battery. So I had the alt checked and the stator came back as bad, luckily it was still under warranty so I replaced it. The next morning, same thing low voltage but this time it was .3 volts. I took the battery to Walmart to have it checked , it was less than a year old. After waiting 1hr and a half it came back good. So I get back home and check amp draw with everything off( even underhood light) and I had a 3.5 amp draw. I checked every in cab fuse one at a time with no change. I had to leave for work shortly after. As I return this weekend I bought a new voltage regulator from advance. Hooked it up and no fix, the amp draw is now dang near 5 amps. I'm needing help with this one guys. Oh and my battery light is on as well.

 

[Guffey6]

Ok guys I was doing more reading and I disconnected both battery negative cables to read amperage and it went from 5 amps with the drivers side battery still connected to virtually zero when disconnected. Could it be that I've had a bad battery this entire time? The voltage reads 11.64v right now.

 

[yan7gin]

This will help you for battery voltage. If you have another battery from another car, put it in the truck and check if you still have the draw

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[ArcticDriver]

Ok guys I was doing more reading and I disconnected both battery negative cables to read amperage and it went from 5 amps with the drivers side battery still connected to virtually zero when disconnected. Could it be that I've had a bad battery this entire time? The voltage reads 11.64v right now.

If you are testing the batteries then isn't a better method to check Voltage on each fully disconnected battery than to test Amps?

Unhook positive and negative cables for each battery. Fully charge each battery with a wall mounted charger. Unhook charger. Check voltage. Allow to sit overnight and check voltage again. It should still be atleast 12.6 or higher.

 

[Steve83]

...5.3 volts on the cranking battery.

Exactly where were the meter probes when you got that reading, and what meter were you using? Are the meter's batteries good?

I took the battery to Walmart to have it checked...

That's like taking a waffle iron to IHOP to get it checked. A parts store would have been better; a dealership is usually the best. Click this & read the caption:

...check amp draw with everything off...

Again: exactly where & how did you measure this current?

...I bought a new voltage regulator from advance. Hooked it up...

Does your truck have a 1G alternator?



I would have expected it to have a 2G.



If you EVER find a problem with that alternator, I highly recommend you swap to a 130A 3G. It's nearly a bolt-on mod, even when switching from a 1G.

. .

...my battery light is on as well.

You should start by thoroughly inspecting, cleaning, & tightening (ONLY if necessary) the battery terminals. If any are damaged, ruined, or the wrong kind, follow the instructions in this photo album to replace them:



After the batteries are fully charged (SLOWLY <5A for several hours), check idling voltage at 3 locations: across each battery, and from the alternator case to its output stud. Post the results.

 

[Guffey6]

Steve, my leads were reading from neg post to pos. Post and was 5.3v .

I took it to Walmart because I bought it from there less than a year ago, and was hoping I could get a new one.

I checked for amps bridging from the negative post to the negative battery cable.

From what i am seeing it's looking like I have a 1g Part number 7072 .

 

[Guffey6]

Ok I took the drivers side battery to advance auto this morning. Turns out it's good, the guy said it was just low voltage, they charged it, I took it home and swapped the batteries. Now I have no problems. No current draw and every thing is back up to snuff. So far..

 

[bugman]

Just as a FYI, unless your truck has been rewired you do not have a starter battery but both batteries are used for starting. They are wired in parallel which means that they are connected positive to positive and negative to negative.

Also while it really doesn't matter it is a good idea to replace both batteries at the same time.

 

[ArcticDriver]

Ok I took the drivers side battery to advance auto this morning. Turns out it's good, the guy said it was just low voltage, they charged it, I took it home and swapped the batteries. Now I have no problems. No current draw and every thing is back up to snuff. So far..

Its not typical to have only one of your batteries at 5.3 volts.

These batteries are hooked up in (EDIT: Parallel) and after a few days of sitting like yours were, they should have both been near the same voltage.

The fact you had such a large amp draw probably indicates a voltage imbalance between the two batteries. You said you had the "starter" battery (primary battery) charged and tested and it was reported "good". Did you do anything with the other battery? You should really have it charged and tested as well.

 

[Guffey6]

Yes both batteries were tested and charged on different days. Both came back good. I had no current draw after swapping the batteries. I drove the truck about 45 minutes today. Tomorrow morning I will see what the voltage reads.

 

[Steve83]

These batteries are hooked up in series...

Parallel. Connecting batteries in series ADDs their voltage; connecting them in parallel adds their AMPERAGE (or Amp-hours).

Tomorrow morning I will see what the voltage reads.

Disconnect EITHER terminal from EITHER battery (one is enough) while you measure voltage across each battery's posts.

 

[ArcticDriver]

Parallel. Connecting batteries in series ADDs their voltage; connecting them in parallel adds their AMPERAGE (or Amp-hours).Disconnect EITHER terminal from EITHER battery (one is enough) while you measure voltage across each battery's posts.

Senior moment. Thanks for catching it.

As for either terminal from either battery, you won't ever break me of the habit of removing negative first. (Unless I am working on our Ford Jubilee).
:winking:

 

[Guffey6]

This morning everything was as it should be. Thanks for all the help, and all the great information! ?


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[yan7gin]

glad you got it figure out